willisthelandy

New Member
Heres a good one - completely baffling me

just replaced the front 11" shoes on my 88, new springs etc now all is well for about 1/2 mile then the brakes seem to get stronger and stronger, pedal travel reduces, until they are on fully...leave it for 10minutes come back and all is well again...lubed all the linkages, taken the hubs off again!, new fluid, still doing it...driving me to insanity

All Help or ideas gratefully appreciated
 
are the new springs that pull the shoes back in the same length and resistance as the ones that came off it? is there anything stopping or slowing the shoes returning back to normall "rest" position...

did you change the wheel cylinders??

just some thoughts off the top of my head, hope this helps
 
internally collapsed flexi brake hose? works like a valve so u can push the fluid past wif the pedal but springs aint strong enuf to shuv it back thru, it oozes back thru after a bit
 
Thanks for the replies

New springs looked exactly the same as the old ones but as for tension not sure...haven't changed the slave cylinders as yet altho I do have some new ones...adjusters fully backed off...collapsed brake pipe, now that would make sense, they don't look the best...new lines on order will give that a go see what happens

Thanks again
 
Did you, on the off-chance bleed the brakes after fitting the new shoes, and DID you by that same chance use the two-man pedal press and spanner twiddle, method?
If so, good chance that pushing the brake pedal down well beyond normal range of action, wiped crud off a normally unswept portion of the cylinder. This usually makes the seals go, but can equally get wiped into the ports.
This can play havoc with the master cylinder valving.
So, when you brake, pumps fluid in, but clocked valve wont let it return to the reservior and the brakes 'pump-up' similar to the effect of a crushed or internally collapsed brake hose.
Could also be at the other end, where the old slave cylinders, expanded to maximum operating range to work thin shoes have been squashed back into a zone of operation they havent worked in along the cylinders length for a very long time.
 
Have you adjusted the master cylinder to eliminate all play in the pedal?
There must be some play or the brakes won't release correctly and will tighten with use until they lock up.
 
Did you, on the off-chance bleed the brakes after fitting the new shoes, and DID you by that same chance use the two-man pedal press and spanner twiddle, method?
If so, good chance that pushing the brake pedal down well beyond normal range of action, wiped crud off a normally unswept portion of the cylinder. This usually makes the seals go, but can equally get wiped into the ports.
This can play havoc with the master cylinder valving.
So, when you brake, pumps fluid in, but clocked valve wont let it return to the reservior and the brakes 'pump-up' similar to the effect of a crushed or internally collapsed brake hose.
Could also be at the other end, where the old slave cylinders, expanded to maximum operating range to work thin shoes have been squashed back into a zone of operation they havent worked in along the cylinders length for a very long time.

Hello

Haven't bleed the brakes as yet, once I had put the new shoes in the pedal changed from nearly touching the floor to half way and on a quick spin round the block seemed to work much better so have left the bleeding for the moment...only noticed the pads locking up just the other day, I'm sure it didn't do it straight after changing the shoes
 
Ahhh :)

I would still recommend bleeding the brakes, might not be the cause of your problem but they often need doing.
 
Hi,

What you describe is typical of an over adjusted master cylinder push-rod ...... but if you didn't touch it ..... ???

Swollen hose? Yes, but I would expect it to take full effect after the first pump.

Sticky pedal? IE - pedal does not dangle loosely. Can't get my mind what effect that will have.

Pedal return spring missing from under dash, or is that only S2s

Blocked vent hole in reservoir cap can cause a multitude of symptoms. Try driving with cap removed, but don't go far without it.

For your information, the pedal should be 6.25" above the floor, measured vertically. There should be SOME free play - I usually set adjustment for a lot less than the book says.

In your position, I would provoke the problem, then slacken the outlet union on master cylinder till it leaks a bit, then tighten. If problem has gone away, suspect the master cylinder. If not, problem is further down the system. Are all four brakes getting hot?

Yes, sticky cylinders could cause this problem, so repeat, how many brakes are geting hot? Also, I would not expect a sticky cylinder to creep back .... but nothing is impossible.

602
 
Do you have a servo? Could that have somehow gone wrong and be pulling the brakes on? Disconnecting the vacuum pipe to the servo and then testing the brakes with the engine running could prove or disprove that theory.
 
I have changed my series front brake pipes many times and one occasion I found one rubber pipe collapsed inside with no fluid being able to pass through.therefore it is possible to restrict the flow. Be especialy careful to buy the correct size replacement pipes as different male threads and rubber bores have been used. have you got a servo? if the air intake is not closing fully when de accelerating the brakes can be inefficient
check the spings are fitted correctly as the haynes manual. the spring should fit between the shoe and the post not across the shoes which is a common fault this has a tendency to fully retract the hydraulic cylinder which may cause the fluid and pedal to raise

Geoff
 

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